Metallic Layer Etching with Oxidized Hardmask Sidewall Trimming
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Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in achieving precise etch profiles of metallic layers due to the limitations of current etching methods, particularly as feature sizes shrink and aspect ratios increase, leading to issues like metal re-sputtering on dielectric hardmask layers.
Innovation Solution
The use of an ion-free etchant gas to trim and oxidize the sidewalls of dielectric hardmask layers, followed by anisotropic etching with the remaining hardmask as a mask, allows for precise control of the etch profile of underlying metallic layers, preventing metal re-sputtering and enabling efficient shrinking of the hardmask margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to pattern metallic layers, then etching can be performed, but metal re-sputtering occurs on dielectric hardmask layers and etch profile precision deteriorates
Solution Approach 1:
The patent extracts and removes the oxidized sidewall portion of the dielectric hardmask layer using ion-free etchant gas. By selectively removing only the oxidized portion rather than etching the entire hardmask layer, the method prevents metal re-sputtering while maintaining precise etch profile control on the metallic layer.
Solution Approach 2:
The patent applies preliminary oxidation to the sidewall of the dielectric hardmask layer before the main etching process. This oxidation creates a distinct layer that can be selectively removed, preparing the hardmask structure in advance to prevent metal re-sputtering during subsequent etching operations.
2Manufacturing precision
If feature sizes are scaled down and aspect ratios are increased, then semiconductor device density is improved, but etching challenges and process complexity increase
Solution Approach 1:
The patent segments the etching process into distinct stages: oxidation of the sidewall, selective removal of the oxidized portion, and then metallic layer etching. This segmentation allows each step to be optimized independently, enabling precise feature size control even at scaled dimensions while managing overall process complexity.
Solution Approach 2:
The patent changes the chemical and physical parameters of the etching environment by using ion-free etchant gas and applying oxidation. These parameter changes enable better control over etch profiles at reduced feature sizes and higher aspect ratios, addressing the challenges posed by device scaling.
3Reliability
If ion-free etchant gas is used to trim hardmask sidewalls, then metal re-sputtering is prevented, but additional process steps are required
Solution Approach 1:
The patent merges the oxidation step and the etching step into a closely integrated process sequence. The oxidation is performed in-situ on the sidewall, and the subsequent removal of the oxidized portion uses the same ion-free etchant gas system, combining multiple functions into a unified process flow that maintains hardmask integrity while minimizing overall complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves the etch profile of metallic layers by maintaining hardmask integrity and preventing metal re-sputtering, thereby enhancing the precision and reliability of semiconductor device fabrication.
Implementation Method 1
oxidizing a sidewall of the patterned first hardmask layer
Implementation Method 2
removing the oxidized sidewall of the first hardmask layer by flowing an ion-free etchant gas
Data Source
AI summary
A method for fabricating semiconductor devices is disclosed. The method includes sequentially forming at least a first hardmask layer and a second hardmask layer over a metallic layer. The method includes patterning the second hardmask layer and then the first hardmask layer. The method includes oxidizing a sidewall of the patterned first hardmask layer. The method includes removing the oxidized sidewall of the first hardmask layer. The method includes etching the metallic layer using a remaining portion of the first hardmask layer as a mask.